Composition containing novel modifier

ABSTRACT

A composition comprising a binder and a residue wherein the residue comprises a blend of polypropylene, styrene butadiene rubber and calcium carbonate. The residue is a novel material derived as a coproduct from the medium-pressure depolymerization of nylon 6 carpet. The compositions are useful as road asphalt, asphalt roof membranes, molding compounds, and plastic lumber such as palisades and spacers.

RELATED APPLICATIONS

This application claims the priority date of provisional applicationSer. No. 60/094,949, filed Jul. 31, 1998.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a composition containing a binder and amodifier. More specifically, this invention relates to a compositioncontaining a binder and a modifier which is a novel material derived asa coproduct from the medium pressure depolymerization of nylon 6 carpet.The compositions are useful as road asphalt, roof membranes, moldingcompounds, and plastic lumber.

2. Brief Description of Related Art

Asphalt is commonly used as a roadway material due to its low materialcost and ease of application. In general, maintenance is required torepair cracks and holes in the pavement, often at significant costs.This has become a major issue for our nation in recent years due tohigher traffic volumes, increased loads and higher tire pressures.Clearly, improved overall performance grades of asphalt which will leadto a reduction in maintenance costs are desirable. The performanceimprovements, however, have to be achieved in a manner that does notincrease significantly the base asphalt paving economics.

It is known that a variety of polymer additives, such as polyethyleneand thermoplastic elastomers, can improve the level of field performanceof asphalt. The use of polyethylene as a modifier improving rheologicalproperties for paving asphalt has been disclosed in, for example, D. N.Little and G. Legnani, (1989). The use of polyethylene as a modifier forroofing asphalt to increase coating viscosity and hardness has beendisclosed in, for example, U.S. Pat. No. 4,328,147. The addition ofelastomers to asphalt has been shown to improve flow characteristics andreduce cracking of the asphalt, especially at low temperatures due toheavy loads. U.S. Pat. Nos. 4,547,399, 4,835,199, and 5,002,987exemplify the use of elastomers in asphalt. U.S. Pat. No. 5,744,524teaches a polymer-modified asphalt which further comprises a dispersingagent to generate a polymer modified asphaltic composition with gooddispersion characteristics. A. Usmani (1996) teaches a carboxylatedmonomer/polymer additive to a filled, polypropylated asphalt to improvethermostability. Addition of elastomers, however, presents difficultiesat higher use temperatures as the asphalt becomes sticky, and ruttingoccurs in high traffic areas of the roadway. Solutions to this problemare sought by adding graft copolymer resins comprising a rubberypolymeric substrate and a rigid polymeric superstrate, as described forexample in U.S. Pat. No. 5,710,196.

Asphalt is an inexpensive thermoplastic and, therefore, the inclusion ofcostly polymer additives is economically unattractive despite theproperty gains observed. Therefore, polymer additives are as yet notwidely used in asphalt paving despite the improvements they impart inpavement properties such as crack resistance and reduced rutting. Theuse of less costly plastic modifiers derived from waste polymer sourcesis an option being studied by a number of investigators, for example, inV. J. Peters and D. V. Holmquist (1992), and U.S. Pat. No. 5,702,199.The use of waste carpet material as a modifier for asphalt has beendisclosed in U.S. Pat. No. 5,665,447 and in G. S. Gordon et al. (1993),and as a modifier for concrete in Y. Wang et al. (1993). None of thesethree disclosure teaches nor suggests the use of coproduct produced inmedium-pressure depolymerization of nylon waste carpet as a modifier forcompositions.

SUMMARY OF THE INVENTION

In this invention, the addition of coproduct, a unique blend ofpredominantly polypropylene (PP), styrene butadiene rubber (SBR) andcalcium carbonate (CaCO₃), leads to a significant improvement in theperformance of the asphalt. The unique combination of the three maincomponents results in a range of asphalt property enhancements that arenot achievable by simple physical combination of the individualcomponents. In addition, the coproduct, since it is derived fromrecycled carpet through a novel process, has a very favorable costposition compared to other polymer-based asphalt modifiers.

The solution to the problem in the art is a composition comprising abinder and a residue wherein the residue comprises a blend ofpolypropylene, styrene butadiene rubber and calcium carbonate. Theresidue is a unique coproduct derived from the medium-presssuredepolymerization of nylon 6 carpet, a novel process taught incommonly-assigned U.S. Pat. No. 5,681,952.

In one preferred embodiment, coproduct is mixed with hot asphalt as thebinder. The level of coproduct added to the asphalt is between about 0.5weight % (wt %) to about 80 wt %, more preferably between about 2 wt %to about 50 wt % and most preferably between about 5 wt % to about 30 wt%. This embodiment results in a significant reduction in the creepstiffness and improvement of the Theological properties at both high andlow temperature in the resultant binder-residue composition compared tothe binder alone. For instance, healing, the rebonding of microcracksduring rest periods between loads, is improved in this embodiment.Addition of aggregate to this embodiment yields a composition useful forpaving applications.

In another preferred embodiment, coproduct is mixed with a plastic asthe binder. The level of coproduct added to the plastic is between about0.5 wt % to about 80 wt %, more preferably between about 2 wt % to about70 wt %, and most preferably between about 9 wt % to about 60 wt %.

In another preferred embodiment, coproduct is mixed with a thermosetpolyester as the binder. The level of coproduct added to the plastic isbetween about 0.5 wt % to about 80 wt %, more preferably 2 wt % to about50 wt %, and most preferably about 5 wt % to about 20 wt %.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic diagram of the invention.

FIG. 2 shows a plot of polypropylene molecular weight distributions forcarpet backing and coproduct.

FIG. 3 shows a plot of coproduct flow behavior at 230° C.

FIG. 4 shows a plot of complex viscosity as a function of frequency at25° C. for three comparative examples.

FIG. 5 shows a plot of complex viscosity as a function of frequency at0° C. for three comparative examples.

FIG. 6 shows a plot of complex viscosity as a function of frequency atseveral different temperatures for two comparative examples.

FIG. 7 shows a plot of complex viscosity as a function of frequency at25° C. for a comparative and two inventive examples.

FIG. 8 shows a plot of complex viscosity as a function of frequency at0° C. for a comparative and two inventive examples.

FIG. 9 shows a plot of G′ as a function of frequency at severaltemperatures for a comparative example.

FIG. 10 shows a plot of G″ as a function of frequency at severaltemperatures for a comparative example.

FIG. 11 shows a plot of G′ as a function of temperature at variousfrequencies for a comparative example.

FIG. 12 shows a plot of G″ as a function of temperature at variousfrequencies for a comparative example.

FIG. 13 shows a plot of tan(δ) as a function of temperature for acomparative example at various frequencies.

FIG. 14 shows an effect of frequency on T_(G″max) for a comparativeexample.

FIG. 15 shows a plot of G′ as a function of reduced frequency for acomparative example at various temperatures.

FIG. 16 shows a plot of G″ as a function of reduced frequency for acomparative example at various temperatures.

FIG. 17 shows a plot of shift factors as a function of temperature for acomparative example.

FIG. 18 shows a plot of G′ versus G″ for a comparative example atvarious temperatures.

FIG. 19 shows a plot of G′ versus G″ for a comparative example atvarious frequencies.

FIG. 20 shows a plot of G′ as a function of temperature for threecomparative examples at a specific frequency.

FIG. 21 shows a plot of G″ as a function of temperature for threecomparative examples at a specific frequency.

FIG. 22 shows a plot of G′ as a function of reduced frequency for threecomparative examples.

FIG. 23 shows a plot of G″ as a function of reduced frequency for threecomparative examples.

FIG. 24 shows a plot of shift factors as a function of temperature forthree comparative examples.

FIG. 25 shows a plot of G′ as a function of reduced frequency for twocomparative examples and two inventive examples.

FIG. 26 shows a plot of G″ as a function of reduced frequency for twocomparative examples and two inventive examples.

FIG. 27 shows a plot of shift factors as a function of temperature fortwo comparative examples and two inventive examples.

FIG. 28 shows a plot of G′ versus G″ for three comparative examples.

FIG. 29 shows the linear region in a plot of G′ versus G″ for threecomparative examples.

FIG. 30 shows a plot of G′ versus G″ for two comparative examples andtwo inventive examples.

FIG. 31 shows the linear region in a plot of G′ versus G″ for twocomparative examples and two inventive examples.

FIG. 32 shows the four transition regions in a plot of log G′ as afunction of temperature for a comparative example.

FIG. 33 shows the four transition regions in a plot of log G′ versus logG′ for a comparative example.

FIG. 34 shows a plot of permanent deformation as a function of cycle fora comparative example.

FIG. 35 shows a plot of permanent deformation as a function of cycle foranother comparative example.

FIG. 36 shows a plot of average permanent deformation as a function ofcoproduct content.

FIG. 37 shows a plot of average resilience modulus as a function ofcoproduct content.

FIG. 38 shows a plot of shear modulus as a function of temperature for acomparative example and two inventive examples of bulk moldingcompounds.

FIG. 39 shows a plot of tan(δ) as a function of temperature for acomparative example and two inventive examples of bulk moldingcompounds.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The term “binder” as used herein refers to any material which functionsto hold together residue in a solid state or mass, as the result ofcooling, heating, or curing. Thus, binder includes: bitumen, whichincludes asphalt and coal tars; polymers, elastomers and rubbers,thermosets, thermoplastics, and liquid crystalline polymers, andmixtures, blends, and copolymers thereof. Thermosets include: thermosetpolyester, vinyl ester resins, phenolic resins, silicone resins, epoxyresins, furan resins, polyurethane resins, aminoplastics such asurea-formaldehyde resin, melamine-formaldehyde resin, cyanate esterresins, and etc. Thermoplastics include: polyolefins such as low densitypolyethylene (LDPE), high density polyethylene (HDPE), polypropylene,polystyrene, acrylic plastics such as poly(methyl methacrylate),poly(vinyl chloride), poly(vinyl acetate), polyamide and polyimide suchas nylon 66, aromatic nylon such as Kevlar®, polyacetal, polycarbonates,etc. Also included are the thermoplastics that have derivativescontaining p-phenylene groups such as polyphenylenes ethers,polyphenylene sulfides, polysulfones, and polyester resins such aspoly(ethylene terephthalate), and poly(butylene terephalate),polycaprolactones, etc. Also included are liquid crystal polymers suchas thermotropic and lyotropic polymers such as liquid crystal polyestersand amides, etc. Mixtures, blends, and copolymers thereof which includeswaste streams from, for instance, recycling facilities are alsoincluded. Binder excludes caprolactam.

The term “residue” as used herein refers to the novel coproduct of themedium pressure depolymerization of nylon 6 waste carpet, using no addedcatalyst, taught in commonly-assigned U.S. Pat. No. 5,681,952, herebyincorporated by reference. Coproduct comprises calcium carbonate,styrene butadiene rubber and polypropylene, the main components of wholecarpet backing material. Coproduct comprises essentially no residualnylon 6 polyamide material, that is, less than about 5% residual nylon 6material, and preferably less than about 1% residual nylon 6 polyamidematerial. Coproductmay contain up to about 5% or other polymersincluding polyester, nylon 66 and other minor degraded polymercomponents found in commercially-available carpets. “Residue” and“coproduct” are used interchangeably herein.

Coproduct is the critical component to this invention. Coproduct is asolid at room temperature and is produced in the medium pressuredepolymerization process described in commonly-assigned U.S. Pat. No.5,681,952. As illustrated in the schematic in FIG. 1, in theabovementoned process, shredded carpet 12, having polyamide face fiber,is converted via depolymerization 14 into two products: high purityepsilon caprolactam 16 and a solid residue 18, referred to in thisinvention as coproduct. It has been found through extensiveexperimentation that coproduct can be added to a variety of binders 20to create novel and useful compositions 22.

To understand the composition of coproduct, an appreciation of theinitial carpet construction is helpful. Carpet is a composite materialcomprising a face fiber, such as nylon 6, nylon 66, polypropylene, woventhrough a primary backing typically made of polypropylene. A secondarybacking, again typically made of polypropylene, is attached to theprimary with an adhesive layer of styrene butadiene rubber latex filledwith calcium carbonate. The polypropylene/styrene butadiene rubber latexconstruction accounts for approximately 95% of all residential andcommercial carpets in the United States. A typical composition of acarpet shows the face fiber at 45% by weight, calcium carbonate at 35%by weight, styrene butadiene rubber at 9% by weight, and thepolypropylene at 11% by weight. The medium-pressure depolymerizationprocess (U.S. Pat. No. 5,681,952) converts the nylon 6 fraction of thecarpet into epsilon caprolactam. The remaining components of the carpet,mainly polypropylene, styrene butadiene rubber and calcium carbonate areformed into a unique blend, referred to as coproduct. As a result of theextreme conditions encountered during the depolymerization, thesenon-nylon components undergo some level of mixing and possible chemicalmodification. As such the resulting coproduct is a unique blend of thethree main non-nylon components. A typical composition for the coproductis about 63% calcium carbonate, about 18% polypropylene and about 19%styrene butadiene rubber by weight. The manner in which these three maincomponents are combined is critical to the coproduct's ability to modifythe properties of asphalt. In no way should coproduct be considered as aphysical mix of the three components. Analysis by microscopy, solventextraction, thermal gravimetric analysis (TGA) and Fourier transforminfrared spectroscopy (FTIR) shows that the calcium carbonate particlesare essentially coated with styrene butadiene rubber. Also, from gelpermeation chromatography, the polypropylene fraction has asignificantly reduced molecular weight and narrowed molecular weightdistribution compared to the molecular weight and molecular weightdistribution of the polypropylene fraction prior to depolymerization. Inaddition, infrared studies suggest that the carbon-carbon doublecharacter of the SBR latex has changed (for instance, by hydrogenation).In other words, the conditions encountered in the proprietarydepolymerization process create a unique blend of the three maincomponents that make up coproduct.

Asphalt is a complex mixture of hydrocarbons derived from the fractionaldistillation of crude oil where the heaviest residue is processed intodifferent grades of asphalt. An elemental analysis of asphalt shows thatthe composition by weight is approximately 82-86% carbon, 8-11%hydrogen, 1-1.5% oxygen, and 1-6% sulfur, with trace amounts ofnitrogen, vanadium, nickel and iron (S. J. Rozeveld et. al., 1997).Asphalts are typically divided into four main groups: asphaltenes,resins, aromatics and saturates (Whiteoak,1990). Asphaltenes are thehighest molecular weight constituents, being highly polar complexaromatic materials. Asphaltenes constitute 5-25% of the total asphaltand have a hydrogen/ carbon ratio of 1.1:1. Asphaltenes are believed tobe sheets of aromatic and naphthenic ring structures held together byhydrogen bonds (Altgen and Harle,1975). Resins are very polar in natureand act as a dispersing agent for the asphaltenes. The aromatics andsaturates are the lightest molecular weight group in asphalt. Thearomatics are the lowest molecular weight naphthenic compounds, and thesaturates consist of both aliphatic hydrocarbons and alkyl naphthenesand alkyl aromatics. Together, the aromatics and saturates (oily phase)constitute the major portion of asphalt (40-50%). Asphalt is oftenregarded as a colloidal system consisting of high molecularasphaltenes/resin micelles dispersed in a lower molecular weight oilymedium.

Asphalt binder, modified or not, is typically mixed with aggregate toproduce an asphalt mixture. “Aggregate” refers to stones or gravel. Theperformance of asphalt cement-aggregate systems (asphalt concrete) isinfluenced by the Theological properties of the asphalt binder as wellas other factors including mix composition, aggregate properties, andvoid content. Pavement grade asphalt concrete undergo a short cyclicload under normal service conditions, and a large accumulation ofpermanent strain will develop over time, leading to failure. The areasof importance critical to the long term performance of flexiblepavements are a). stiffness and stiffness-temperature relationships, b).fatigue resistance, c). permanent deformation resistance, d).low-temperature cracking resistance, and e). strength characteristics.

To test the performance changes of asphalts containing varying levels ofadditive the specifications and procedures set down in the StrategicHighway Research Program (SHRP) “Background of SUPERPAVE™ ASPHALT BINDERTEST METHODS”, hereby incorporated by reference to the extent necessaryto complete this disclosure, were followed. The tests performedincluded: penetration (hardness), dynamic shear rheometry (DSR),rotational viscometry (RV), bending beam rheometry (BBR), and directtension tester (DTT). The asphalt mixtures are aged following the twoSHRP procedures, rolling thin film oven (RTFO) and pressure aging vessel(PAV). These procedures are intended to simulate hardening (durability)characteristics. After both types of aging, the asphalt mixtures arere-tested using the SHRP tests listed above. All the tests were done atthe Texas Transporation Institute (TTI).

The asphalt compositions of the present invention can be prepared bytechniques known in the art These techniques include both low and highshear mixing techniques, preferably carried out at elevatedtemperatures. The temperature used should not exceed the degradationtemperature of the asphalt, although it may vary based on the chemicalcomposition of the asphalt. The coproduct may be added as a drymaterial. Its size may be reduced as desired by any method known in theart.

The other compositions of the present invention likewise may be preparedby techniques known in the art. Elevated temperature, if used, shouldnot exceed the degradation temperature of the binder, and may varyaccordingly. The coproduct may be added as a dry material. Its size maybe reduced as desired by any method known in the art.

Testing Methods

The hardness/penetration test was performed according to ASTM D-5. Eachspecimen was tested at 100 grams force for 5 seconds at 77° F. (25° C.).

Dynamic shear rheometry (DSR) using a Bohlin Rheometer CVO instrumentwas used to characterize the viscous and elastic behavior of samples bymeasuring the complex shear modulus (G*) and phase angle (δ) at a fixedfrequency of 10.08 radians per second (rad/s). The measurement was doneaccording to the guidelines in “Background of SUPERPAVE™ ASPHALT BINDERTEST METHODS”. The following fixed parameters were used throughout theexamples that related to the DSR measurement: 12% strain amplitude; 25millimeter (mm) plate diameter; 1 mm plate gap; and 5 minutesequilibrium time.

Bending beam rheometry (BBR) was performed using a ThermoelectricBending Beam Rheometer from Cannon Instrument Company and was doneaccording to the guidelines in “Background of SUPERPAVE™ ASPHALT BINDERTEST METHODS”. This test uses engineering beam theory to measurestiffness of a small asphalt beam sample under a creep load of 980milli-Newton (mN) (100 gram) force. The beam dimensions were: length was125 mm, width was 12.70 mm and thickness was 6.35 mm. The forcecalibration constant for the rheometer was 0.149 mN/bit with adeflection constant of 0.16 micrometer per Newton. The sample beam wasplaced in a freezer at −10° C., then quickly transferred to a testingchamber at −16° C. The soak time at −16° C. was 30 minutes. A 1997version of the Cannon BBW w 1.0 software was used for data computation.

To measure complex viscosity, G′and G″, a Rheometrics RDA-II was used tomeasure dynamic properties of the various asphalt samples as a functionof frequency and temperature. A 2000 g-cm force rebalance torquetransducer was used, along with 25 mm parallel plates. The frequencyrange was 0.1 rad/s to 100 rad/s with five points per decade. Thetemperature range used was −40° C. to 30° C. with 5° C. steps. The plategap was 4 mm. The frequency/temperature sweep data were analyzed withRheometrics' TTS package contained in the Orchestrator® operatingsoftware. Mastercurves were generated from the raw data using horizontalshifting, residual minimization as the computational method, cubicspline interpolation, and the highest accuracy setting.

¹³C solid-state NMR spectra were acquired under conditions ofcross-polarization and magic-angle spinning (CPMAS) at spinning speedsranging from 3-5 kHz on a Chemagnetics CMX-300 solid-state NMRspectrometer. ¹³C spin-lattice relaxation rates in the rotating framewere measured by employing a spin lock following cross-polarization witha 45 kHz spin locking field. No ¹H decoupling was applied during thespin lock, however, decoupling was applied during the acquisition of thesignal.

RTFO-aging and PAV-aging were performed in accordance with “Backgroundof SUPERPAVE™ ASPHALT BINDER TEST METHODS”. The temperature wascontrolled to the nearest 0.1° C.

Permanent deformation of asphalt and gravel mixtures was assessed byevaluating the potential for the mixtures to deform under repeated loadtriaxial testing at 40° C. with no confinement and a repeated deviatoricstress of 35 kPa. Deformation was recorded by means of two linearvariable differential transformers (LVDT) positioned 180 degrees apart.Testing was performed using a servo-hydraulic MTS machine.

In order that those skilled in the art will be better able to practicethe invention, the following examples are given by way of illustrationand not by way of limitation.

EXAMPLES Coproduct Characterization

To characterize the chemical and physical properties of the coproduct,the following instrumental techniques were employed: elemental analysis,TGA, gel permeation chromatography (GPC), FTIR, rheometry, andcalorimetry. Samples of carpet backing layer were also subjected to GPCand FTIR for comparison purposes.

Elemental Analysis of the Coproduct

The level of calcium was established via a standard method (SW846/6010), using an Inductive Couple Plasma (ICP) technique. Four samples ofthe coproduct were taken at distinctly different times during theoperation of the depolymerization pilot plant. The results of thecalcium analysis are shown in Table 1, expressed as calcium carbonate.These results reflected the variability of the post-consumer carpetfeedstock typically provided to the depolymerization pilot plant. Anaverage value of about 63 wt % in the coproduct was observed.

TABLE 1 Sample 1 Sample 2 Sample 3 Sample 4 CaCO₃, wt % 58.1 58.4 61.870.7

Characterzation of Coproduct by TGA

The TGA experiments were conducted using a Seiko Instrument RTG 220thermal analyzer. About 15 milligrams of sample was placed in a platinumpan, and the material was heated from about 23° C. to 1000° C. at aheating rate 10° C./min under an air atmosphere. The air source wasbottled compressed air. The flow rate of the air was maintained at 200milliliter per minute (ml/min) during the experiment.

The weight loss and the rate of weight loss of ground coproduct in airrevealed five steps in the decomposition. The temperatures andcorresponding weight loss percentages of these five steps are shown inTable 2. The first three steps may account for the decomposition ofpolyolefins (such as polypropylene) and SBR; the fourth is due to theoxidation of char/carbon residue into carbon dioxide; the fifth step isthe decomposition of CaCO₃ to CaO and CO₂. TGA of coproduct passed once,twice or three times through a cage mill showed the same steps ofdecomposition and similar weight losses at each step.

TABLE 2 Weight Loss @ Temperature Temperature (° C.) at Maximum (° C.),Wt % Rate of Weight Loss ≦38 349 499 600 1000 1 2 3 4 5 Ground coproduct0.0 −10.0 −30.8 −34.7 −60.5 313 425 456 517 732 Cage- 1 Pass 0.0 −10.3−30.4 −34.9 −60.3 325 450 463 525 731 milled 2 Passes 0.0 −11.5 −31.6−36.2 −61.6 325 432 456 525 734 coproduct 3 Passes 0.0 −10.5 −31.1 −35.8−61.0 335 — 460 525 734

Both PP and SBR could have been carbonized, yielding a low amount ofchar, before the material is oxidized to form CO₂ at temperature above400° C. The decomposition of CaCO₃ to CO (the weight loss at 1000° C.)provided an estimate of the inorganic fraction of the coproduct.

Both the elemental analysis and the TGA confirmed that coproduct has aninorganic fraction which is approximately 63% of the total coproductcomposition. Also, the TGA results support the claim that the coproductis an inextricable mixture of the three major components.

Determination of Molecular Weight Parameters by GPC

The molecular weight distribution of the PP in two samples each of theoriginal carpet backing and the coproduct was determined by GPC. The GPCanalysis was performed on a Waters 150C. instrument with two PLgellinear mixed-B columns at 135° C. The mobile phase was1,2,4-Trichlorobenzene at a flow rate of 1.0 ml/min, and the sampleinjection volume was 200 microliter (μl). The dissolution of samples wascarried out at 150° C. on a wrist action shaker for 16 hours. Allsamples were analyzed with a refractive index detector and calibratedagainst universal polypropylene standards. The data analysis of thechromatograms was handled with Nelson 2600 system software. The GPCresults are listed in Table 3 and are shown graphically in FIG. 2.

TABLE 3 Sample ID Mz¹ Mpeak² M_(w) ³ M_(n) ⁴ M_(w)/M_(n) Mz/M_(w)Mhh+/Mhh−⁵ Carpet Back Sample #1 255,500 107,500 127,100 32,900 3.9 2.08.3 Carpet Back Sample #2 245,400 101,000 125,000 34,900 3.6 2.0 8.4Coproduct Sample #1 17,300 8,200 10,000 4,500 2.2 1.7 7.7 CoproductSample #2 17,100 8,100 9,700 4,100 2.4 1.8 7.8 ¹“Mz” is the Z and Z + 1average molecular weight. ²“Mpeak” is the maximum peak value from adifferential molecular distribution curve. ³“M_(w)” is the weightaverage molecular weight in daltons. ⁴“M_(n)” is the number averagemolecular weight in daltons. ⁵“Mhh+/Mhh−” is the ratio of molecularweights at the half height of the polymer distribution.

It can be seen from Table 3 and FIG. 2, that as a result of thedepolymerization process, the PP was degraded with a molecular weightreduction of an order of magnitude. The PP polydispersity, M_(w)/M_(n)was reduced from about 3.75 to 2.3 as a result of conditions in thedepolymerizabon reactor. These results were consistent with theexpectation from the literature on polypropylene degradation.

FTIR Analysis of Coproduct

Coproduct was analyzed using an FTIR (Bruker Model FTS 88) spectrometer.Coproduct samples were analyzed before and after extraction withmethylene chloride. Reference pieces of the original carpet backing werealso analyzed. The extraction was as follows: 5 wt % of ground coproductwas added to methylene chloride in a sealed glass tube. The mixture wasagitated at 24° C. for 24 hours. The liquid phase was decanted and thesame amount of fresh methylene chloride was added to the glass tube.This was repeated three times.

The dried, washed coproduct samples were analyzed in powder form eitheras the bulk powder or as a 3% mixture in potassium bromide (KBr) using adiffuse reflectance sampling accessory. Analysis of the coproduct bulkpowder produced a non-linear absorbancy response, with weaker peaksappearing to be more intense than they should be. Mixing the powderedcoproduct sample with KBr powder reduced this effect.

The IR spectra of the coproduct sample before and after washing withmethylene chloride show that the major components in both samples wereCaCO₃ and PP with SBR as a minor component. Table 4 lists peaksidentifying each component.

TABLE 4 Component IR Peaks (cm⁻¹) CaCO₃ 2518, 1796, ˜1450 (broad), 874PP 2929, 1462, 1378, 1160, 999, 973, 899, 840, 809 SBR 3060, 3020, 756,699

The FTIR analysis showed that washing with methylene chloride removedSBR, but left the ratio of PP to CaCO₃ unchanged. Subtracting the“after” washing spectrum from the “before” washing spectrum andnormalizing (i.e. removing) the CaCO₃ and PP components of the spectrumshowed the difference in relative levels of SBR. In addition, there wasanother series of peaks corresponding to a low level of nylon indicatingthat not all the nylon was converted to caprolactam in thedepolymerization process.

There was a weak, broad absorbency in the region ˜1760-1650 cm⁻¹ that isnot due to the nylon. This absorbency may indicate a low level oxidationof the PP.

Determination of Flow Behavior of Coproduct by Rheometery

The flow behavior of coproduct at 170° C., 190° C., and 230° C. wasevaluated using a Rheometrics RDA-II, a parallel plate rheometer. Theparallel plates were 25 mm with a gap of 4 mm. The coproduct sample waskept at the desired temperature for about 5 minutes prior to the test.The flow behavior data at 230° C. of the molten coproduct is shown inFIG. 3. The flow behavior of the coproduct was highly shear thinningeven at relatively low shear rates. Such behavior can be fitted well toCarreau's model (Tadmor and Gogos, 1979) in Eq. (1)

η(γ)=μ₀{1+(κ_(1γ))⁷⁸ ^(₂) }^((κ) ^(³⁻) ^(1)/κ) ^(₂)   (1)

where μ₀ is the zero shear viscosity, γ is the shear rate, and κ₁, κ₂,and κ₃ are constants. The parameters μ₀, γ, κ₁, κ₂, and κ₃, in theCarreau's model are listed in Table 5 for coproduct at all threetemperatures; units for the parameters are provided, unless theparameter is dimensionless. Also listed is R² which is a measure of thegoodness of fit of the data to the model.

TABLE 5 Parameters for Carreau's model Temp, Shear Rate Range, ° C. 1/sμ₀, Pa · s κ₁, s κ₂ κ₃ R² 170 0.000065-0.0056  1.22 × 10⁷ 0.00105 0.1810−6.9718 0.9352 190  0.00011-0.0059 2.334 × 10⁶ 1402.4 0.3883 −0.07050.9946 230  0.00213-1.0989 1.678 × 10⁶ 5.303 × 10⁴ 2.5985  0.2901 0.9282

Deternination of Heat Content

The coproduct samples were sent to Froehling & Robertson, Inc. fordetermination of its heat content (BTU) by ASTM 2015-85. The heatcontent of the samples ranged from 6100 BTU/lb to 6914 BTU/lb ofcoproduct. An average value of 6600 BTU/lb was established. This levelof heat content makes coproduct attractive as an alternative fuelsource, eg. in cement manufacturing.

Experiment 1: Asphalt Binders

Four types of asphalts, utilized in the Strategic Highway ResearchProgram (SHRP), were employed as binders in the invention and were theComparative Examples (Comp. Ex.). The SHRP Binder Characterization andEvaluation Program selected eight asphalts, designated core asphalts andcoded as AAA-1, AAB-1, AAC-1, AAD-1, AAF-1, AAG-1, AAK-1 and AAM-1, forextensive characterization. The results are available in BinderCharacterization and Evaluation Vol. 2: Chemistry, (1993) StrategicHighway Research Program, National Research Council, SHRP-A-368. Thefour asphalts chosen for use herein vary in chemical and physicalproperties. For example, AAD has a high percent of asphaltenes, and AAGand AAM have a very low percent. AAA, AAD and AAG have similar numberaverage molecular weights, while AAM has a much higher number averagemolecular weight. These are listed in Table 6 with their classification,and their performance grade (PG) as established by the SHRP. Additionalinformation about these polymers is available in S.-C. Huang, et al.(1998).

TABLE 6 Comp. Ex. Name of Asphalt Classification Performance Grade A AAGAR4000 PG 58-10 B AAM AC-20 PG 64-16 C AAD AR4000 PG 58-28 D AAA AC-10PG 58-28

Coproduct is fairly brittle, due to the high calcium carbonate content,and can be readily ground to redure size. In the Inventive Examples(Inv. Ex.), coproduct at three different particles sizes was mixed atdifferent temperatures and in different amounts into three differenttypes of asphalt binders. “Chip” was the largest particle size and“cage-milled” was the smallest particle size, being a fine powder.“Chip” is about 0.25 to 1 inch (6.35 mm to 25.4 mm) in diameter; “groundchip” is about 5 to 100 micrometer(μM) and “cage-milled” is about 1 to30 μM. The low level of 7.5 weight percent (wt %) for coproduct additionto binder represents a typical level for polyolefins being used as anadditive in asphalt applications, while the high level (20 wt %) is atypical level for inorganic fillers. The weight % is the weight ofcoproduct divided by the sum of the weights of the asphalt and thecoproduct.

Inv. Exs. 1 through 9 were prepared using a two-liter, three-neck resinreaction kettle equipped with a temperature controller and an agitatorwhich was a two-inch helical screw impeller. The speed of the agitationwas kept at about 800 revolutions per minute (rpm). About 500 grams ofmolten asphalt at 275° F. was discharged into the resin kettle and thematerial was heated to the desired temperature. When the temperaturereached the desired temperature, the appropriate amount of coproduct wasslowly added to the mixing kettle. After the discharge of the coproductwas complete, and the temperature returned to the desired level, mixingwas continued for an additional 30 minutes. Finally, thecoproduct-modified asphalt was discharged into sample containers forperformance evaluation.

Inv. Exs. 10 through 13 were prepared using a two-liter Waring blender.A glass wool blanket was wrapped around the blender container tominimize heat loss. The blender container (with blanket) was placed inan oven at 180° C. for about ten minutes. About 400 grams of molten AADasphalt (Comp. Ex. C) at 170° C. was discharged into the blendercontainer. The desired amount of coproduct was quickly added to thecontainer and the mixture was mixed vigorously at about 20,000 rpm. Themixing time was 1.0 minutes for Inv. Exs. 11 and 12, and 2.5 minutes forInv. Exs. 10 and 13. In these four Inventive Examples, the temperatureloss due to convection cooling was less than 10° C. Thecoproduct-modified asphalt was then discharged into sample containersfor performance evaluation.

As part of the design of the experiment, replicate measurements weremade on Inv. Ex. 1, and selected other Inventive Examples. Where morethan one measurement was taken, to indicate the replicate, themeasurements are labelled “i”, “ii”, etc as appropriate after theInventive Example number. In addition, separate batches were preparedfor some formulations; these are indicated by the Inventive Examplenumber followed by a letter (eg. 2a).

Sediment was found in all the Inventive Examples as a result of thecoproduct containing CaCO₃. As expected, the coproduct dispersion inasphalt improved with finer particle size, with the cage-milledcoproduct having the best dispersion. At higher temperatures (190° C.vs. 150° C.), the coproduct was more readily dispersed, mostly due tothe melting of the PP fraction (crystalline melting for PP is 165° C.).

Comp. Exs., A, B and C, and Inv. Exs. 1 through 9 were tested forhardness/penetration in accordance with ASTM D-5. These data arepresented in Table 7.

TABLE 7 Comp. Inv. Content Location Location Location Hardness Ex. Ex.Asphalt wt % 1 2 3 Average increase⁶ A AAG 0 53 50 53 52 — 1i AAG 13.040 40 40 40 23% 1ii AAG 13.0 36 38 37 37 29% 1iii AAG 13.0 38 39 38 3827% B AAM 0 60 60 60 60 — 2a AAM 20.0 25 26 24 25 58% 2b AAM 20.0 31 2723 27 55% 3 AAM 7.5 38 36 36 37 38% 4 AAM 20.0 42 41 40 41 32% 5 AAM 7.535 34 35 35 42% C AAD 0 133 126 120 126 — 6a AAD 7.5 90 91 86 89 29% 6bAAD 7.5 78 72 80 77 39% 7 AAD 20.0 59 58 57 58 54% 8 AAD 7.5 85 85 84 8533% 9 AAD 20.0 68 66 66 67 47% ⁶The hardness increase was calculated bydividing the difference between the average hardness of the unfilledasphalt and filled asphalt by the average hardness of the unfilledasphalt.

Comp. Wx. A was the hardest unfilled asphalt used in this experiment. Asshown in Inv. Exs. 1i through 1iii, addition of coproduct to 13 wt %yielded an increase in hardness for this asphalt. An increase inhardness as the result of coproduct addition was also evidenced in Inv.Exs. 2 through 9. These Inventive Exs. further demonstrated that thehardness generally increased with the weight percent of coproduct.

These and subsequent data demonstrated that the dominant factor ininfluencing the physical properties of the modified asphalt compared tothe unmodified asphalt was the extent of coproduct loading (weightpercent) in the asphalt composition.

Dynamic shear rheometry was used to characterize the viscous and elasticbehavior, at intermediate to high temperatures, of Comparative andInventive Examples by measuring the complex shear modulus (G*) and phaseangle (δ). As explained in “Background of SUPERPAVE™ ASPHALT BINDER TESTMETHODS” (1994) and “SUPERPAVE™ Performance Graded Asphalt BinderSpecification and Testing” (1997), high values of G* and low values of δare needed to achieve rutting resistance. The ratio, G*/sin (δ), is usedto incorporate both important parameters into one term for specificationpurposes. In Table 8, the data for the Comparative Examples measured atthree different temperatures is presented. These data were fullyconsistent with what was expected based on their PG classification. InTable 9, the data for Inv. Exs. 1 through 13 is presented.

TABLE 8 G* G*/sin(δ) Strain Amp Comp. Ex. Asphalt Test Temp. (kPa) δ(degrees) (kPa) (%) Test Status⁷ A AAG 64° C. 0.9622 90.0000 0.962211.8700 Failed 58° C. 2.2773 89.6000 2.2773 11.8700 Passed 52° C. 3.903889.1000 3.9045 11.7500 Passed B AAM 64° C. 1.2378 86.9000 1.2378 12.1100Passed 58° C. n.d.⁸ n.d. n.d. n.d. — 52° C. 6.0857 83.6000 6.123512.3500 Passed C AAD 64° C. 0.6498 86.8000 0.6508 11.9300 Failed 58° C.1.3553 84.7000 1.3610 11.9800 Passed 52° C. 2.8622 82.6000 2.886011.7300 Passed ⁷In the Performance Graded Asphalt Binder Specification(found in “Background of SUPERPAVE ™ ASPHALT BINDER TEST METHODS” or“SUPERPAVE ™ Performance Graded Asphalt Binder Specification andTesting”), the G*/sin(δ) must meet or exceed 1.00 kPa at the testtemperature to pass. ⁸“n.d.” means not determined. Given that Comp. Ex.B had a G*/sin(δ) value in excess of 1.00 kPa at 64° C., it is expectedto pass at 58° C. as well.

TABLE 9 Inv. Content G* δ G*/sin(δ) Strain Amp Test Ex. Asphalt (wt %)Test Temp. (kPa) (degrees) (kPa) (%) Status 1i AAG 13.0 64° C. 2.113786.3000 2.1181 12.140 Passed 52° C. 13.0490 84.000 13.0930 11.760 Passed1ii AAG 13.0 64° C. 1.6942 84.6000 1.7018 12.280 Passed 52° C. 9.460783.6000 9.5203 12.060 Passed 1iii AAG 13.0 64° C. 1.7994 89.0000 1.799712.220 Passed 52° C. 11.0780 87.6000 11.0880 11.730 Passed 2a AAM 20.064° C. 2.9729 81.0000 3.0060 12.290 Passed 52° C. 14.1910 78.800014.4660 12.190 Passed 2b AAM 20.0 64° C. 3.2250 80.4000 3.2990 11.900Passed 52° C. 24.3300 76.0000 24.9580 12.190 Passed 3 AAM 7.5 64° C.3.1249 80.8000 3.1660 12.170 Passed 52° C. 14.3990 78.2000 14.709012.180 Passed 4 AAM 20.0 64° C. 6.7049 76.1000 6.9069 12.380 Passed 52°C. 29.2290 74.000 30.5160 12.000 Passed 5 AAM 7.5 64° C. 2.8090 82.30002.8346 12.010 Passed 52° C. 13.9760 77.1000 14.3400 12.030 Passed 6a AAD7.5 64° C. 1.1740 83.9000 1.1810 12.060 Passed 52° C. 4.933 79.30003.4870 12.130 Passed 6b AAD 7.5 64° C. 1.3468 84.3000 1.3535 11.940Passed 52° C. 3.9310 78.7000 6.0478 11.900 Passed 7 AAD 20.0 64° C.4.384 81.0000 4.801 12.120 Passed 52° C. 14.2730 73.7000 14.7280 12.350Passed 8 AAD 7.5 64° C. 1.2850 84.1000 1.2919 12.090 Passed 52° C.3.7152 79.1000 3.8202 11.870 Passed 9 AAD 20.0 64° C. 2.8494 82.90002.8712 12.040 Passed 52° C. 12.7450 77.7000 13.0440 12.440 Passed 10 AAD7.5 64° C. 1.0920 84.40 1.0956 11.93 Passed 11 AAD 20.0 64° C. 1.889684.20 1.8994 11.68 Passed 12 AAD 7.5 64° C. 1.3570 84.20 1.3639 11.92Passed 13 AAD 20.0 64° C. 1.9068 82.50 1.9068 12.18 Passed

The data in Table 9 demonstrate that the values of G* and δ for thedifferent coproduct-and-asphalt compositions were highly dependent onthe extent of coproduct loading, test temperature and frequency used intesting. The addition of coproduct to any of the Comparative Examplesimproved the performance. Notably the addition of coproduct to AAD(Comp. Ex. C vs Inv. Exs. 6 through 13) and to AAG (Comp. Ex. A vs. Inv.Ex. 1) yielded compositions that passed the test at 64° C. Even with anaddition of only 7.5 wt % of coproduct, AAD-based compositions (Inv.Exs. 6, 8, 10 and 12) passed the DSR test at 64° C. Thus, the additionof the coproduct greatly affected the dynamic shear behavior of theasphalt binders evaluated, and enhanced their performance.

DSR was also performed at four higher temperatures on samples of alarger batch of Inv. Ex. 11. The larger batch quantity was needed toprovided sufficient material for studies of coproduct-modified asphaltwith aggregate added. For the larger batches, a large colloid-mill(Eppenbach colloid mill from Gifford-Wood Company, Husdon, N.Y.)equipped with a 3.5 gallon tank was used to prepare thecoproduct-modified asphalt binders. The tank was wrapped with a heatingband to maintain temperature during mixing. About 2000 grams of moltenasphalt at 170° C. was discharged into the collioid mills at atemperature about 170° C. The desired amount of ground chip coproductwas added to the container quickly. The mixture was mixed vigorously ata maximum setting. The mixing time was about 10 minutes. The temperatureof the mixture was higher than 170° C. by about 2° C. to 5° C. due toviscous dissipation in mixing. The mixture was then discharged intosample containers for performance evaluation. The mixture appeared tohave good dispersion, and the samples were stored in a cool room withcontrolled humidity (50° F.@ 50% relative humidity).

The DSR data for the four higher temperature studies are in Table 10and, when compared to Comp. Ex. C data in Table 8, show that theaddition of 20 wt % coproduct to AAD asphalt dramatically extended thehigher temperature performance (both G* and δ) of AAD asphalt fromfailing at 64° C. to passing at 76° C.

TABLE 10 Inv. Test Content G* δ G*/sin(δ) Strain Amp Test Ex. Temp.Asphalt wt % (kPa) (degrees) (kPa) (%) Status 11 52° C. AAD 20 14.273075.7000 14.7280 12.35 Passed 64° C. AAD 20 3.3384 81.0000 3.3801 12.12Passed 72° C. AAD 20 1.5466 83.7000 1.5561 12.27 Passed 76° C. AAD 201.0676 82.9000 1.0757 12.16 Passed

Asphalt filled with an inorganic filler were prepared to compare to thecoproduct-modified compositions. Comp. Exs. E, F and G were comprised of20% hydrate lime in asphalt binder as shown in Table 14. The lime was−200 mesh. These Comparative Examples were prepared using the three-neckresin reaction kettle and helical screw impeller used for Inv. Exs. 1through 9 and were mixed at 170° C. The data are shown in Table 11. Incontrast to Inv. Exs. 7 and 9, Comp. Ex. E failed the test at 58° C.Comp. Ex. F showed that the 20 wt % hydrate lime actually reduced theG*/sin(δ) compared to the same asphalt in the absence of hydrate lime(Comp. Ex. A) at 64° C. The 20 wt % hydrate lime only slightly increasedthe G*/sin(δ) value for AAM asphalt (Comp. Ex. B vs Comp. Ex. G). Thesedata suggest the coproduct does not act merely as an inorganic fillerdespite its high proportion of CaCO₃. Furthermore, the benefits ofadding coproduct to asphalt were realized at low coproduct loading (ex.7.5 wt %).

TABLE 11 Comp. Content G* δ G*/sin(δ) Strain Amp Test Ex. Asphalt wt %Test Temp. (kPa) (degrees) (kPa) (%) Status E AAD 20 58° C. 0.899882.800 0.9068 12.02 Failed F AAG 20 64° C. 0.8698 88.300 0.8702 12.02Failed G AAM 20 64° C. 1.3064 86.000 1.3096 12.16 Passed

Bending beam rheometry was used to characterize the viscoelasticcharacteristics of the various compositions at low temperatures inaccordance with the guidelines in “Background of SUPERPAVE™ ASPHALTBINDER TEST METHODS”. In the test, designed by SHRP, a creep load isused to simulate the thermal stresses that gradually build up in apavement when temperature drops. Two parameters are evaluated with BBR.Measured stiffness (creep stiffness) is a measure of how the asphaltresists constant loading. To pass the test detailed in “Background ofSUPERPAVE™ ASPHALT BINDER TEST METHODS”, it should not exceed 300 mPa atthe 60 second time point. The m-value is the creep rate and is thechange in asphalt stiffness with time during loading. The testguidelines require the m-value to be equal to or greater than 0.300 at60 seconds. The data presented in Table 12 was measured at −16° C.

TABLE 12 Comp. Inv. Measured Ex. Ex. Asphalt Content wt % Force, mNDeflection, mm Stiffness, MPa m-Value A AAG 0 1004 0.171 473.00 0.334 1iAAG 13.0 985 0.114 697.00 0.263 1ii AAG 13.0 1010 0.103 791.00 0.2331iii AAG 13.0 985 0.110 722.00 0.253 B AAM 0 987 0.422 189.00 0.316 2aiAAM 20.0 994 0.211 380.00 0.245 2aii AAM 20.0 1007 0.255 318.00 0.2612bi AAM 20.0 988 0.265 301.00 0.267 2bii AAM 20.0 1009 0.261 312.000.275 3 AAM 7.5 996 0.336 238.00 0.282 4 AAM 20.0 1015 0.297 276.000.268 5 AAM 7.5 990 0.317 251.00 0.279 C AAD 0 976 1.632 48.20 0.484 6aiAAD 7.5 990 1.595 50.00 0.513 6aii AAD 7.5 1001 1.245 64.80 0.512 6biAAD 7.5 1007 1.669 48.60 0.470 6bii AAD 7.5 990 1.104 72.30 0.463 7 AAD20.0 991 0.896 89.20 0.446 8 AAD 7.5 1011 1.194 68.30 0.460 9 AAD 20.01001 0.743 109.00 0.421 10 AAD 7.5 1000 2.009 40.1(?) 0.532 11 AAD 20.0997 0.675 119 0.451 12 AAD 7.5 1015 1.548 52.9 0.523 13 AAD 20.0 9970.815 98.6 0.471

These data showed that the addition of 13 wt % coproduct to AAG (Inv.Ex. 1) increased the stiffness and lowered the “m-value” of the originalasphalt binder (Comp. Ex. A). Similarly, addition of coproduct to AAMasphalt at 7.5 wt % (Inv. Exs. 3 and 5) and at 20 wt % (Inv. Exs. 2 and4) increased the stiffness and lowered the m-value compared to theoriginal binder (Comp. Ex. B).

In contrast, an unusual behavior in coproduct-modified AAD asphalt wasobserved that was not observed in the coproduct-modified AAM or AAGasphalts. Specifically, addition of 7.5 wt % coproduct to AAD (Inv. Exs.6, 8, 10 and 12) resulted in a very marginal increase in stiffness andan increase in m-value compared to the unfilled AAD asphalt (Comp. Ex.C). At high coproduct loading, the behavior followed that for coproductfilled AAM and AAG: at 20 wt % coproduct, the addition of coproductincreased the stiffness and decreased the “m-value” of AAD asphalt.

Although the nature of the interactions between coproduct and AADasphalt are not understood, it is suspected that at low coproductconcentration, the coproduct may plasticize AAD. At 7.5 wt % coproduct,the increase in the “m-value” of AAD asphalt (see FIG. 3b) suggests thatthe coproduct may have changed the morphology of the asphalt network.

BBR was also performed on aged asphalt samples having 20 wt % coproduct.The samples were aged by two consecutive aging processes in accordancewith SHRP guidelines. The first was rolling thin film oven (RTFO) andthe second was pressure aging vessel (PAV). The coproduct-loaded sampleswhich were subjected to the aging process came from the large-scalebatch described for Inv. Ex. 11 in Table 10. BBR data for aged samplesis presented in Table 13. The temperature at which the BBR was performedis indicated in the table.

TABLE 13 Results of Bending Beam Rheometer (@ 60 s) Test Measured Comp.Inv. Temperature Deflection, Stiffness, m- Ex. Ex. (° C.) Force mm MPaValue A −16 998 0.176 457 0.260 B −16 976 0.671 117 0.291 C −16 9890.999 80 0.408 11i −12 1002 0.588 137 0.367 11ii 1000 0.48 168 0.347 11−16 992 0.57 142 0.358 11i −18 984 0.196 405 0.273 11ii 1001 0.256 3150.284 11 −22 992 0.139 575 0.233

The data in Table 13 demonstrate, as expected, that aging increasedstiffness and decreased m-value when compared to the correspondingunaged sample. The SHRP guidelines for aged samples are: the stiffnessmust be less than 300 MPa and the m-value must be equal to or greaterthan 0.3 to pass the test at a given temperature. Although not tested,Comp. Ex. C, having a PG 58-28 rating, must pass the test at −18° C.Inv. Ex. 11 did not pass the test at −18° C. or lower, however, it didpass at both −12°C. and −16° C. It is possible that an aged samplehaving a lower level of coproduct loading (7.5 wt %) in AAD would retainthe −18° C. passing status.

In dynamic shear flow, the storage modulus (G′) and the loss modulus(G″) are measures of the elastic and viscous responses of a viscoelasticmaterial. For a given filled viscoelastic system, these quantitiesdepend on frequency (ω), temperature(T), and filler volume fraction(φ_(f)). For dynamic shear measurements, one uses plots of G′ and G″against ω with T and φ_(f). Often, G′ and G″ are plotted against a_(T) ωto construct a mastercurve by superposition, where a_(T) is thetime-temperature shift factor, which varies with temperature.

In the past, efforts have been made to match rheological properties fromsteady shear to dynamic shear measurements at very low values of shearrate or oscillatory frequency. It was Han and coworkers who firstsuggested the use of logarithmic plots to connect elastic and viscousresponses in steady shear flow to dynamic shear measurements. Thesetemperature independent correlations are useful to interpret and compareTheological behavior of different fluids without the need formeasurement at different temperatures and shear rate or oscillatoryfrequency.

Han and Lem (1983) pointed out that in dynamic shear flow, one mayconsider the oscillatory frequency, ω to be an input variable imposed onthe fluid, whereas both G′ and G″ are the output elastic and viscousresponses of the fluid subjected to testing. Therefore, by using theestablished fact that G′ is related to stored energy, and G″ todissipated energy, it was found that the logarithmic plots of G′ againstG″ give rise to temperature independent correlations.

These well developed rheological theories should apply to asphalts.Asphalt itself is a complex low molecular weight thermoplastic whoseTheological properties depend on molecular structure and chemicalcomposition. Therefore, one may surmise that the addition of coproductwould only complicate the rheological properties of asphalt systems,i.e., we are mixing an immiscible blend (mixture of cured styrenebutadiene rubber, polypropylene, and asphalt in coproduct) with asuspension (calcium carbonate filled asphalt).

To further characterize some of the inventive asphalt compositions, theyand the unfilled asphalt binders, were subjected to a range ofoscillatory frequencies and temperatures to measure complex viscosity,G′and G″. Included with these samples were Comp. Ex. D and twocoproduct-filled composition based on this asphalt. Inv. Ex. 14contained 7.5 wt % coproduct added to AAA and Inv. Ex. 15 contained 20wt % coproduct added to AAA.

FIGS. 4 and 5 show plots of complex viscosity against oscillatoryfrequency, ω for AAD, AAM, and AAG at 25° C., and 0° C., respectively.All the asphalts exhibited shear thinning behavior, i.e. viscositydecreased with increasing shear oscillatory frequency. The extent ofshear thinning behavior depended on the type of asphalt and temperature.At high temperatures AAG exhibited higher viscosity than AAD and AAM(FIG. 4). In spite of their low viscosity, both AAD and AAM manifested ahigher propensity to shear thinning in the range of oscillatoryfrequency used in the measurement. In contrast, at low temperatures(FIG. 5), AAG had a higher propensity to shear thinning than AAD andAAM. At low shear rates, AAG exhibited a Newtonian region at anoscillatory frequency<0.4 rad/s at about 25° C. (see FIG. 4). At about5° C., plots of complex viscosity against oscillatory frequency (datanot shown) exhibited one cross-over point (where one curve crossesanother curve) between the curve for AAG and the curve for AAM at about60 rad/s. At about 0° C., the plots of complex viscosity againstoscillatory frequency (FIG. 5) exhibited two cross-over points: onebetween the AAG and AAM curves at about 17 rad/s and one for AAG, AAMand AAD curve at about 40 rad/s.

FIG. 6 shows the relationship of complex viscosity and oscillatoryfrequency for AAD and AAM at several temperatures ranging from 24° C. to−15° C. For AAD and AAM, the propensity for shear thinning increasedwith decreasing temperature. The difference in the viscosity behaviorbetween AAD and AAM decreased with decreasing temperature until theybecame identical at 15° C. The absence of cross-over points, related totemperature alone or to various transitions (i.e., such as molten,rubbery, or glass transition), implies that AAD and AAM are similar typefluids. In contrast, the cross-over in FIG. 5 suggests that AAG may be avery different fluid compared to AAD and AAM in structure andcomposition.

FIGS. 7 and 8 are plots of complex viscosity against frequency for: AAD(Comp. Ex. C), and AAD compounded with 7.5 wt % (Inv. Ex. 6) and 20 wt %coproduct (Inv. Ex. 7), at 25° C., and 0° C., respectively. Bothcoproduct-filled AAD samples exhibited shear thinning, while viscosityincreases with increasing coproduct content. As shown in FIG. 7, at 25°C., AAD viscosity increased with coproduct in the range of oscillatoryfrequency evaluated. At low temperature, 20 wt % coproduct-filled AAD(Inv. Ex. 7) showed a higher tendency toward shear thinning than 7.5 wt% coproduct-filled AAD (Inv. Ex. 6) and unfilled AAD (Comp. Ex. C). At0° C., there was one cross-over point between Inv. Ex. 7 and Inv. Ex. 6samples at about 25 rad/s (FIG. 8).

Two types of master curves (logarithmic plots of G′ and G″ against a_(T)ω; logarithmic plots of G′ against G″) were used to interpret theTheological behavior of AAD (see FIGS. 9 and 10, and Table 14). Thelogarithmic plots of G′ against G″ were constructed according to theprocedure of Rong and Chaffey (1988) and were used to determine thetransition regions and the absolute glass transitions at G″_(max) ofpure and coproduct-filled asphalt binders.

FIGS. 9 and 10 show G′, and G″ versus frequency at various temperaturesfor AAD (Comp. Ex. C). FIGS. 11 and 12 show G′, and G″ versustemperature at various frequencies. As expected, these figuresdemonstrate that the viscoelastic responses of AAD depend very much onthe frequency and temperature. FIG. 13 gives the plots of tan (δ) vs.temperature at various frequencies ranging from 0.1 to 100 rad/s. Unlikethe plots of G″ against temperature in FIG. 12 where the maximum of G″was visible, the maximum of tan (δ) was not easily observable.

In viscoelastic materials, long chain segment motions due to chemicalbonds or association have a profound effect on the loss factors such astan (δ) or G″/G′, and G″ of the dynamic mechanical properties. The lossfactors are very sensitive to molecular motion. For example, in theglassy region (around −15° C.) the dynamic shear modulus (G′) in FIG. 11showed a small degree of change while the loss factors exhibited dampingpeaks (FIG. 12). According to Murayma (1987), the largest loss peak isassociated with the glass-transition temperature (Tg). Rodriguez (1982)asserted that the maximum energy loss is always at the glass transitiontemperature (Tg), and the maximum in the peak of G″ (G″_(max)) can beinterpreted as Tg. This temperature is referred to herein as Tg @G″_(max). Values of Tg @ G″_(max) are presented in Table 14. As evidentin FIG. 12, the value of Tg @ G″_(max) depends on frequency. Indeed, aplot of Tg @ G″_(max) against log_(e) (frequency) in FIG. 14 showed afairly good correlation.

FIGS. 15 and 16 show mastercurves for G′ and G″, respectively, againsta_(T) ω for AAD (Comp.Ex. C). As seen from these figures, the datapresented in FIGS. 9 and 10 can indeed be shifted with an arbitraryshift factor to a reference temperature of 25° C. Thetemperature-dependence of the shift factor is shown in FIG. 17, in whicha maximum is seen at −35.3° C.

FIGS. 18 and 19 show the relationship of G′ and G″ for AAD at varioustemperatures, and frequencies, respectively. The data was the same asthat used in FIGS. 9 to 11. The plot of G′ against G″ is the same inboth figures and is virtually independent of temperature and frequency.Unlike typical polymer melts, the linear portion in the viscous flowregion on the logarithmic plots of G′ against G″ could be extended to ahigher G″ (˜10⁶ Pa). This suggests that AAD asphalt has a relativelysmall rubbery region because of its low molecular weight. As seen inFIGS. 18 and 19, the linear portion of the logarithmic plots (theviscous flow region) of G′ against G″ for AAD could be predicted byEq.(2).

G′=κ*(G″)^(χ)  (2)

where κ=0.0541 and χ=1.1713.

FIGS. 20 and 21 give the plots G′, and G″ against T at ω=10 rad/s (or1.59 Hz), the frequency specified by SHRP in the DSR measurement. Bothfigures give an illustration of the performance classification for theseasphalts studied. As seen from Table 6, AAM is a PG 64-16 performancegraded asphalt, AAD a PG 58-28, and AAG a PG 58-10. Although in FIG. 20,AAG shows higher shear modulus at temperature below 25° C. than both AAMand AAD, its shear modulus has a higher sensitivity to temperature aboveTg than both AAM and AAD. As seen from FIG. 21 and Table 14, among theasphalts evaluated, AAD has the lowest Tg, and hence it can maintain itsflexibility at temperatures around −28° C.

FIGS. 22 and 23 give mastercurves of G′, and G″ against a_(T) ω (reducedfrequency), respectively for AAD, AAM, and AAG. Thetemperature-dependent behavior of the shift factor at a referencetemperature of 25° C. is shown in FIG. 24. Clearly AAG is a verydifferent fluid compared to AAD and AAM in viscoelastic behavior. Thisfinding is consistent with our earlier discussion on flow behavior. Dataderived from these graphs are presented in Table 14.

FIGS. 25 and 26 give mastercurves of G′, and G″ against a_(T) ω,respectively for AAD (Comp. Ex. C), Inv. Exs. 6 and 7, and AAM (Comp.Ex. B). The temperature-dependent behavior of the shift factor at areference temperature of 25° C. is shown in FIG. 27. Note a maximum inthe temperature range tested was not observed for the two InventiveExamples. In FIGS. 25 and 26, with increasing coproduct concentration,it was observed that the viscoelastic behavior (even thetemperature-dependent behavior of the shift factor) of coproduct-filledAAD matched that of AAM. This observation, that coproduct addition canenhance the performance of AAD asphalt, providing properties similar toAAM, was consistent with the other measurements made on thiscomposition.

FIG. 28 plots G′ against G″ for AAD, AAM, and AAG. FIG. 20 gives anillustration of the linear region in the plots G′ against G″ for AAD,AAM, and AAG. Similarly, FIG. 30 gives the plots G′ against G″ for AAD,Inv. Exs. 6 and 7, and AAM. FIG. 31 gives an illustration of the linearregion in the plots G′ against G″ for AAD, Inv. Exs. 6 and 7, and AAM.As seen from these figures, the plot of G′ against G″ was virtuallyindependent of temperature. As discussed earlier, the linear portion ofthe logarithmic plots of G′ against G″ in FIGS. 29 and 31 can beextended up at G″ about 10⁶ Pa. This suggests that the pure andcoproduct-filled asphalt binders have a relatively small rubbery regionbecause of the low molecular weight. As recorded in Table 14, Eq. (2)can be used to describe the linear region on the logarithmic plots of G′against G″ for all the asphalt binders and modified asphalt binders.

TABLE 14 Flow Region and Glass Transition Region in the logarithmicplots of G′ against G″ Viscous Flow Region: Comp. Inv. Content G′ =κ*(G″)^(χ) Glass Transition Region Asphalts Ex. Ex. wt. % κ χ R² G″max(Pa) G′ (Pa) tan (δ) aτω (rad/s) AAG A 0.0 0.00022 1.4928 0.999 6.78 ×10⁶ 8.97 × 10⁶ 0.756 115 1 13.0 1.18523 0.9470 0.995 8.80 × 10⁶ 1.60 ×10⁷ 0.548 40 AAM B 0.0 0.01323 1.2819 0.999 4.92 × 10⁶ 1.02 × 10⁷ 0.4801855 3 7.5 0.03381 1.2188 0.999 5.68 × 10⁶ 1.48 × 10⁷ 0.384 43400 2 20.00.07076 1.1772 0.999 4.84 × 10⁶ 1.09 × 10⁷ 0.444 2106 AAD C 0.0 0.005411.1713 0.998 5.56 × 10⁶ 9.63 × 10⁶ 0.578 4310 6 7.5 0.11682 1.1155 0.9996.53 × 10⁶ 1.31 × 10⁷ 0.498 11689 7 20.0 0.14801 1.1028 1.000 5.74 × 10⁶1.32 × 10⁷ 0.434 7065 AAA D 0.0 0.01617 1.2467 0.999 7.00 × 10⁶ 1.15 ×10⁷ 0.610 19313 14 7.5 0.02823 1.2058 0.997 6.79 × 10⁶ 1.16 × 10⁷ 0.5876949 15 20.0 0.02535 1.2463 0.992 1.01 × 10⁷ 3.84 × 10⁶ 0.381 667000

It was reported by Rong and Chaffey (1988) that the four transitionstates observed in the conventional logarithmic plots of modulus againsttemperature/frequency/time as seen in FIG. 32 can be translated into thelogarithmic plots of G′ against G″ in FIG. 33. Rong and Chaffeyrecommended the use of the logarithmic plots of G′ against G″ toconstruct a mastercurve to interpret the viscoelastic response ofmaterial because it does not involve an arbitary shift factor. Asillustrated in FIG. 33, they defined:

1. The glassy state when G′ is greater than G′ at G″_(max) or d log G′/dlog G″ is negative.

2. The glassy transition where G′ at G′ (G″_(max)) or d log G′/d log G″is infinite.

3. The rubbery behavior, when G′ is less than G′ at G″_(max) or d logG′/d log G″ is positive but is not a constant.

4. The viscous flow or molten region is where G′ is less than G′ atG″_(max) or d log G′/d log G″ is positive and a constant.

The parameters obtained from the viscous flow regions and the glasstransition region appear to the performance grading of the asphaltevaluated. A smaller value of χ (d log G′/d log G″) in the viscous flowregion implies that the asphalt may provide lower temperatureflexibility. On the other hand, a smaller value of tan (δ) at G″_(max)in the glass transition region suggests that the asphalt may providehigh temperature resistance. As seen from the Table 14, Inv. Ex. 7 thathas a similar χ value to AAD (Comp. Ex. C) and a smaller value of tan(δ) at G″_(max) compared with AAM (Comp. Ex. B). This would suggest thatthe performance grading of AAD should be potentially around PG 76-28.

NMR has been a technique of growing interest to characterize themolecular motion of asphalts. Solid-state NMR has not been widelyapplied to these types of asphalts until recently. Netzel pointed outthat solid state NMR spectra can be more advantageous than thesolution-state NMR because carbon types in different crystalline andamorphous phase structure can be quantified. Both the ¹³C NMR spectraand the spin lattice relaxation rate in the rotating frame (T₁ _(ρ) _(C)_(⁻¹) ) were examined on the selected asphalts and asphalt compositions.All of the asphalt samples have nearly the same CPMAS spectrum, implyingsimilar chemical composition. There is a broad aliphatic componentcentered at ˜30 ppm and an aromatic component at ˜125 ppm. The aliphaticresonance has some structure, indicating some discreteness in thechemical structures monitored across the lineshape.

Since the spectra of all the samples were nearly identical, ¹³Crelaxation measurements were performed to detect possible differences inthe molecular mobility. T₁ _(ρ) _(C) _(⁻¹) relaxation is an indirectmeasure of the spectral density of the motional correlation function atthe frequency of the spin lock, ω₁/2π, in this case, ˜50 kHz. ¹³Cspin-lattice relaxation rates in the rotating frame across the aliphaticpart of the lineshape at approximately the position indicated arepresented in Table 15. Though variable temperature experiments arefurther required to measure the correlation times of the motions,certain trends can already be seen in the data of the various samples.

TABLE 15 Comp. 30 ppm 25 ppm 22 ppm 16 ppm Ex. Inv. Ex. Asphalt Wt %Additive (sec⁻¹) (sec⁻¹) (sec⁻¹) (sec⁻¹) B AAM AAM 0.52 — 0.38 0.31 2AAM 20 wt % coproduct 0.53 — 0.31 0.27 C AAD AAD 0.81 — 0.59 0.67 7 AAD20 wt % coproduct 0.51 0.38 0.26 0.35 H AAD 20 wt % limestone 0.71 —0.54 0.52 E AAD 20 wt % hydrated lime 0.60 — 0.52 0.42

AAD (Comp. Ex. C) showed rapid relaxation rates at different positionsacross the lineshape. This is an indication of rapid chain mobility. AAM(Comp. Ex. B), which has superior rheological properties, exhibited muchslower relaxation, indicating comparatively more restricted chaindynamics.

The addition of limestone to AAD (Comp. Ex. H) “improves” the product inthe sense of adjusting the molecular dynamics to make it more similar toAAM (Comp. Ex. B). Hard lime continues to “improve” the product (Comp.Ex. E). The addition of 20% coproduct to AAD (Inv. Ex. 7) resulted in amaterial with molecular dynamics nearly identical to AAM. This isconsistent with our conclusion based on Theological properties: additionof coproduct enhances the properties of AAD, making the resultantcomposition quite similar to AAM. The addition of the coproduct to AAM(Inv. Ex. 2) continued to slow the relaxation rates of the materialslightly. Notably, the relaxation times across the entire lineshape wereaffected by the addition of coproduct. This is not simply a case of aslowly-relaxing component being added in at levels at which it dominatesthe average relaxation parameters, but instead appears to be a situationin which the coproduct is modifying the entire matrix by affecting themobility of most of the asphalt chains. The results seem to agree withthe data for tan (δ) at G″_(max) (Table 14). Thus, this is preliminaryevidence for a significant correlation between enhanced rheologicalproperties and molecular mobility as measured by solid-state NMR.

To evaluate rutting (permanent deformation) of asphalt-aggregatemixtures modified with coproduct, coproduct was added at two levels (7.5wt % and 20 wt %) to three different asphalts: AAM, AAD and AAA (Comp.Exs. B, C and D, respectively). A siliceous gravel mixture was used tomake the asphalt-aggregate mixtures. The results were compared withidentical mixtures without coproduct modification of the asphalt. Thetotal binder content was kept constant in all mixtures (totalbinder=asphalt plus coproduct).

The asphalt-aggregate mixtures evaluated were designed to have a highrut potential. Aggregate was chosen such that the resulting mix would bemore susceptible to binder properties. The aggregate type used wassub-rounded, siliceous river gravel. Limestone fines were added to theaggregate blend to improve stability. This formulation proved to behighly rut susceptible in past tests with various binders and additives(D. E. Makunike, “An Evaluation of Permanent Deformation Properties ofCrum Rubber Modified Asphalt Concrete Mixtures”, 1995 Thesis, Texas A&MUniversity). Aggregate for the mix design is shown in Table 16. This mixcontained a top size aggregate of 9.5 mm of uncrushed siliceous rivergravel, and a natural field sand. To increase rut potential, theformulation deliberately included a high field sand percentage of 18%.

TABLE 16 Aggregate Type Sieve size (mm) Percentage retained on sieveLarge river gravel 9.5 15 Small river gravel 4.75 30 Construction sand1.18 37 Field sand 0.6 18

FIGS. 34 and 35 show the permanent deformation as a function of thenumber of cycles for Comp. Ex. D and B, respectively; three replicatesmeasurements were done on each sample (labeled i, ii and iii). FIG. 36shows the average permanent deformation as a function of coproductcontent, and FIG. 37 shows the average resilience modulus as a functionof coproduct content, for compositions using Comp. Exs. B, C and D. Froman analysis of the data, the following trends were noted:

1. For binder AAA, the addition of 7.5 wt % coproduct substantiallyimproved deformation resistance and changed the rate of rutting from atertiary rate of permanent deformation to a steady-state level. Theaddition of 20 wt % coproduct further improved the deformationresistance (when compared to the 7.5 wt % addition) but to a much lesserlevel. This was a logical and favorable trend as it demonstrated thevery substantial improvement with reasonable levels of coproduct (7.5 wt%).

2. For binder AAD, the results compared only the neat binder with the 20wt % coproduct modified binder. The results were similar to those fromAAA in that the additive changed the mixture response from tertiarydynamic creep to steady-state dynamic creep. However, the magnitude ofthe deformation reduction was much greater for AAD than for AAA.

3. For binder AAM, the results were quite different than for AAA andAAD. In this case the addition of 7.5 wt % coproduct significantlyreduced deformation, but not to the level that occurred in AAA or AAD.This was largely due to the fact that the AAM mixtures were more stableto begin with than the AAA and AAD mixtures and unlike the AAA and AADmixtures did not exhibit tertiary dynamic creep. The addition of 20 wt %coproduct dramatically improved rut resistance over the 7.5 wt %additive rate.

4. The addition of the coproduct, like most polymer-type additives, wasasphalt dependent; and the interaction between the coproduct and thebitumen was important. This interaction is controlled by the chemicaland compositional makeup of the asphalt.

Experiment 2: Plastic Binders

The use of coproduct as a filler in plastic lumber products was testedby compounding coproduct with various polymers typically used in themanufacture of plastic lumber. These polymers were derived from recycledplastic products and included: a film fraction (LDPE), a hollow shapedcontainer fraction (HDPE), a cup fraction (PP) and a mixed plasticsfraction. The compounding was done using a twin screw extruder (Wernerand Pfleiderer ZSK 25). Mill-ground coproduct was added to the polymerfraction to achieve approximately pre-determined levels of CaCO₃ in thefinal sample, based on a coproduct composition of about 65 wt % CaCO₃.Control samples were also made using pure CaCO₃ (Socal 2G31UF, supplier)to achieve the pre-determined levels of CaCO₃. The parameters ofextrusion for all four polymer types were: the processing temperaturewas 200° C., the screw-speed was 200 rpm and the vent zone was a vacuum.

Various properties were measured for each sample. To determine CaCO₃content, the samples were burned to a carbonaceous substance and thenashed at 625° C. in a muffle furnace in conformity with ISO 1172. Smallamounts of CaO, which had been formed at this temperature wererecalculated as CaCO₃. The melt volume index (MVI) was determined usinga Gottfert-melt-tester MPR at 230° C. and 2.16 kilogram loading inconformity with ISO 1133. The Charpy impact strength, notched (NCH) andunnotched (UNCH), was determined at 23° C. and −30° C. using aZwick-Pendelschlagwerk in conformity with DIN EN ISO 179 1e. The tensilestrength (TS) and modulus (TM) were determined according to DIN EN ISO527-1 (tensile test) using an Instron test system. The flexural modulus(FM) and the flexural stress (FS) were determined using an Instron testsystem in conformity with DIN EN ISO 178 (three point flexural test).The heat deflection temperature (HDT) was determined using the HDT-Vicattest system (Coesfeld Comp.) in conformity with DIN EN ISO 75 (procedureA). The thermal expansion was determined using the dilatometer TMA 200(Netzsch Comp.) in conformity with DIN 53 752. The specimens wereprepared using an injection molding machine (Aarburg Comp.). Allmeasurements for the thermal expansion tests were carried out understandard conditions (23° C. and 50% relative humidity) on freshinjection molded specimens. These data are reported in Table 17.

TABLE 17 MVI Impact Impact Thermal Co- (cm³/ HDT/ strength, strength, -expansion, Comp. Inv. product CaCO₃ 10 A TS TM 23° C. (kJ/m²) 30° C.(kJ/m²) FS FM α× 10⁵ (K⁻¹) Ex. Ex. Plastic (wt %) (wt %) min) (° C.)(MPa) (MPa) UNCH NCH UNCH NCH (MPa) (MPa) TD⁹ MD¹⁰ I LP¹¹ 0 1.07 1.5636.0 15.50 259.3 n.b.¹² n.b. n.b. 9.12 5.23 343.8 12.5614 43.4421 16 LP9.3 6.05 2.40 35.5 12.60 327.8 n.b. 61.80 n.b. 4.28 6.33 287.4 15.856721.0672 17 LP 23.5 15.26 1.81 38.0 12.10 474.7 n.b. 30.00 135 3.88 9.22500.4 15.8944 21.8335 (2 × n.b.) 18 LP 43.0 27.94 2.09 43.0 10.81 792.252.30 6.93 16.90 2.75 12.88 767.8 17.6575 13.6150 19 LP 59.0 38.33 2.7645.0 9.58 1371.0 9.72 2.85 5.74 2.84 16.05 1087.0 16.1032 9.8986 J LP 09.27 1.14 40.2 15.48 329.7 n.b. 84.60 n.b. 7.75 6.34 416.7 12.128041.0484 K LP 0 20.67 0.70 37.1 15.33 404.4 n.b. 87.20 n.b. 7.14 7.51321.2 13.8356 32.4734 L LP 0 30.82 0.40 37.9 15.75 511.4 n.b. 81.50 n.b.5.44 9.52 572.2 12.6521 28.9618 M LP 0 39.49 0.30 40.3 17.41 695.1 n.b.42.50 165 4.05 11.96 641.9 14.4712 25.3377 (3 × n.b.) N HP¹⁴ 0 1.01 1.2247.0 23.50 958.8 n.b. 25.50 n.b. 3.79 16.30 853.9 11.2967 23.4004 20 HP10.6 6.87 0.80 43.2 21.93 1111.0 n.b. 6.49 64.40 3.58 18.55 1022.011.1659 19.5129 21 HP 30.0 19.46 1.78 46.7 20.21 1454.0 37.40 3.98 18.402.77 22.43 1238.0 11.9384 17.7688 22 HP 39.7 25.78 2.49 47.4 16.881777.0 14.40 2.85 9.34 2.52 25.72 1538.0 10.5066 11.5784 23 HP 57.637.46 4.61 50.9 15.98 2304.0 6.77 1.87 5.31 1.31 27.70 2054.0 10.551510.5961 O HP 0 9.94 0.70 42.7 23.71 1089.0 n.b. 28.60 215 3.77 18.151016.0 10.1920 24.5992 (9 × n.b.) P HP 0 20.49 0.50 44.0 22.40 1276.0n.b. 23.60 78.90 3.28 20.40 1205.0 9.8186 22.7335 Q HP 0 31.49 0.30 47.322.45 1609.0 110.0 13.90 31.10 2.89 23.97 1585.0 9.5276 17.6164 R HP 041.51 0.30 52.0 23.35 1923.0 64.60 9.04 17.00 3.16 28.68 1907.0 9.469317.6012 S PP¹⁹ 0 2.16 11.95 49.8 28.80 1436.0 73.40 4.21 18.80 2.1428.58 1251.0 14.2833 12.7442 24 PP 16.0 10.38 11.39 56.1 26.34 1770.029.40 3.31 13.40 2.27 33.90 1529.0 12.7227 9.9954 25 PP 27.8 18.05 11.6956.5 23.67 2017.0 18.20 2.36 10.80 2.23 36.30 1820.0 11.0257 9.3262 26PP 45.4 29.49 14.10 58.4 19.84 2416.0 10.80 2.20 7.39 2.05 37.39 2095.010.0646 7.7831 27 PP 57.7 37.51 17.26 59.4 17.33 3041.0 6.28 1.96 5.131.22 34.01^(a) 2568.0 8.3881 7.8196 T PP 0 9.48 8.79 50.8 26.93 1631.058.80 3.99 17.90 2.20 30.86 1299.0 13.0815 9.6314 U PP 0 16.74 6.62 53.923.50 1821.0 34.70 3.48 13.00 2.17 33.72 1550.0 11.2601 12.2704 V PP 024.27 5.02 57.1 21.55 2136.0 17.40 2.80 8.73 1.74 36.98 1885.0 10.804010.8612 W PP 0 36.73 2.97 57.1 20.54 2574.0 10.80 1.93 5.51 1.22 37.462357.0 8.5191 10.7480 X¹⁵ MP¹⁶ 0 8.66 19.86 43.5 13.58 929.0 68.60 8.7919.30 3.04 15.20 841.0 18.3807 13.6230 28 MP 21.3 13.85 13.40 43.6 12.781056.0 30.70 6.14 14.60 2.51 16.28 989.0 16.2555 9.6800 29 MP 35.5 23.098.20 43.8 12.19 1100.0 27.00 5.02 12.10 2.34 16.04 969.0 15.0044 12.613730 MP 39.3 25.52 7.40 47.0 10.69 1720.0 8.20 2.48 6.45 2.03 19.28 1378.014.2947 8.0148 31 MP 56.0 36.41 10.70 49.1 11.35 2285.0 5.25 1.74 4.711.22 20.96^(a) 2010.0 11.2151 7.6050 Y MP 0 13.24 15.00 45.3 13.03 970.058.80 8.16 18.00 2.60 15.93 886.0 15.5621 11.6972 Z MP 0 23.77 6.20 44.113.45 1119.0 38.00 6.78 14.10 2.36 16.91 1012.0 16.2925 11.8804 AA MP 045.32 9.50 45.1 12.48 1618.0 15.00 3.74 6.95 1.42 20.90 1467.0 13.266111.1823 BB MP 0 35.05 6.63 46.4 12.94 1317.0 23.00 4.89 9.49 2.26 18.471234.0 11.8159 12.2513 ⁹“TD” stands for transverse direction. ¹⁰“MD”stands for machine direction. ¹¹“LP” stands for LDPE, film fraction.¹²“n.b.” stands for no break. ¹³“HP” stands for HDPE, hollow shapedcontainer fraction. ¹⁴“PP” stands for polypropylene, cup fraction.^(a)These values are flexural stress at break. ¹⁵This sample contained5% CaCO₃ to avoid the formation of hydrochloric acid from the smallquantity of PVC present in this waste stream. ¹⁶“MP” stands for themixed-plastics fraction.

The flowability (MVI) decreases with increasing coproduct addition up toabout 25 wt % CaCO₃ content. Above 25 wt % CaCO₃ content, the organiccontent of coproduct appeared to influence the MVI to get higher values,as the corresponding CaCO₃-alone samples did not show the same increase.With the exception of the mixed plastics samples, the addition ofcoproduct, especially at the higher contents, generally improved the MVIcompared to the unfilled polymer. In contrast, the CaCO₃-filled samplesdecreased the MVI compared to the unfilled polymer.

In contrast to the CaCO₃-filled samples, the increased content ofcoproduct may cause a slight decrease in tensile strength. Thus, thistendency was apparently due to the coproduct's organic components. Boththe tensile and flexural moduli increased dependent on ash contentcompared to the unfilled polymer. At the higher coproductconcentrations, the moduli of the coproduct filled samples areespecially increased compared to the corresponding Comparative Examples,again suggesting this tendency was influenced by the organic componentsof coproduct. The impact strength decreased at higher CaCO₃ contentsdependent on the kind of polymer. The heat deflection temperature wasimproved with increased additive content and thermal expansion isreduced.

These data demonstrated that coproduct could be successfully used as afiller in plastics without adversely affecting processability orproperties, and possibly enhancing some properties.

Subsequently, a plant trial at a commercial recycling plant in Germanywas performed using mixed plastics with about 31 wt % coproduct added toachieve a 20 wt % CaCO₃ content in the composition. Compounding was doneusing a twin screw extruder (Werner and Pfleiderer ZSK 40). Theextrusion parameters were as before. To generate palisades, for use inlandscaping, the following process data for intrusion were used: screwspeed was 44 rpm; injection pressure was 17 bar; injection time was 80seconds; the barrel temperatures were 125° C., 160° C. and 100° C. forsections 1,2 and 3 respectively; the melt temperature was 160-170° C.and the output rate was about 20-25 kilograms per hour. The palisadesample was tested in the same methods described for the data in Table 17and the data are presented Table 18.

TABLE 18 Inv. Ex. 32 CaCO₃ content 20 wt % MVI 8.1 cm³/10 min HDT/A44.0° C. Thermal expansion TD 16.6958 × 10⁻⁵ K⁻¹ MD  7.3578 × 10⁻⁵ K⁻¹Tensile strength  12.38 MPa Tensile modulus 1013.0 MPa Flexural stress 14.67 MPa Flexural modulus  926.5 MPa Charpy impact unnotched 27.0kJ/m² strength, 23° C. notched 6.81 kJ/m² Charpy impact unnotched 13.7kJ/m² strength, −30° C. notched 2.77 kJ/m²

These data demonstrated that coproduct-filled mixed plastics can be madeinto palisades using a process of intrusion. Furthermore, the propertiesof the resultant palisade achieved the standard quality of palisadesfrom the recycling plant.

Experiment 3: Thermosetting Polyester Binder

In view of its high calcium carbonate content, coproduct may have valueas a low cost filler for thermosetting molding compounds such as bulkmolding compounds (BMC), sheet molding compounds (SMC), and thickmolding compounds (TMC). From its composition, coproduct may in factoffer more than just an inorganic filler; potentially it may be alow-profile performance additive. Synergy may be found if it canpartially replace the current calcium carbonate in the currentformulations.

A typical valve cover formulation (Comp. Ex. CC) was used to determinethe effect of coproduct in performance. Comp. Ex. CC utilized thistypical formulation. In the Inventive Examples, two different sizes ofcoproduct particles were used: coarsely ground chip (<32 mesh) andfinely ground and screened (<325 mesh). As seen in Table 19, some of thealuminum trihydrate and all the CaCO₃ were replaced by coproduct in theInventive Examples.

TABLE 19 Comp. Inv. Inv. Materials Function Ex. CC Ex. 33 Ex. 34 VinylEster Resin Resin 22 22 22 (Blended) Peroxide Catalyst Additives Lowprofile, glass 31.5 31.5 31.5 bubles, chopped glass fibers AluminumTrihydrate Flame Retardant 40 30 30 CaCO₃ (Precipitated) Filler 5 0 0Coproduct (<32 mesh) New Filler 0 15 0 Coproduct (<325 mesh) New Filler0 0 15 TOTAL 98.5 98.5 98.5

Resin with peroxide was poured into a 5 kg Baker-Perkin mixer with asigma blade mixing elements. The materials were mixed at a low speed.After 5 minutes, all the fillers were added and mixed for an additional5 minutes. Once the mixture looked very good (as a paste) after 1.5minutes, a Mg(OH)₂ paste was added as a thickener and mixed for anadditional minute. Then the fibers were added to the mixture and thematerials were mixed for another 6 minutes. After the mixing procedure,the materials were poured into a container for thickening aging. Itnormally takes about two or three days to complete the thickeningreactions.

Right after mixing, molding resin was placed into a cavity mold tocompression mold samples to prepare samples for testing as outlined inTable 6.5. Mold temperatures were 320° F. top and 330° F. for 2 minutes.

A 12″×12″×0.110″ plaque was used to determine surface defects. A lowprofile surface is desirable. Only Inv. Ex. 34 having the finely groundand screened coproduct showed an acceptable level of roughness andpitting, comparable to the Comparative Example.

The tensile properties, measured in accordance with ASTM D 638, weremeasured on the three samples and are presented Table 20.

TABLE 20 Comp. Energy at Break Strength at Break Strain at Break Ex.Inv. Ex. (lbs-in) (psi) (%) CC 16.3 7110 1.58 33 6.1 4660 1.00 34 16.67708 1.73

These results were notable since the properties of the typicalformulation (Comp.Ex. CC) were matched by inv. Ex. 34, having coproductat <325 mesh. Thermoset polyester is brittle and is quite poor infatigue resistance. Proper design of resin matrix/toughener, surfacetreatment of fillers and fibers can overcome the problem somewhatHowever, the major issue for this type of bulk molding compound materialis cost Therefore, the surface of the fillers and fibers used is nottreated. The coproduct may provide an advantage because its surface hasbeen “treated” with SBR that itself may be a good coupling agent betweenCaCO₃ and the thermoset resin.

The dynamic mechanical results in FIGS. 38 and 39 were consistent withthe tensile measurement, suggesting that the polyolefins in thecoproduct exhibited a toughening effect. Notably, at higher temperatures(>300°), Inv. Ex. 34 showed a reduced rate of modulus drop withtemperature compared to Comp. Ex. CC. Thus addition of fine meshcoproduct to thermoset polyesters may provide improved propertyretention at higher temperatures. This trend may prove very useful inthat thermoset polyesters are generally known to be brittle and havepoor property retention at higher temperatures.

Experiment 4: Cement Manufacturing Study

The coproduct, due to its high calcium carbonate content and thermalfuel value averaging 6,600 BTU/pound, may be used as a residue toenhance the cement manufacturing process. This use is advantageousbecause it fully employs the components of coproduct.

Cement is a product formed when limestone (calcium carbonate) is mixedwith smaller amounts of sand, clay and iron oxide and calcined attemperatures between 2000 to 3000° F. Such a process is practiced on alarge scale and is known, to those in the industry, as the dry Portlandcement process. The high temperature required for calcination of thelimestone and other reactants is typically generated in a coal firedrotary kiln.

It has been shown by example that the addition of the coproduct to thecement feedstock stream into the lower section of the preheater stagelocated above the top section of the rotary kiln enhances the productionof cement. Two key enhancements are observed. Firstly, there is areduction in the amount of the primary fuel source for the kiln due tothe BTU value of the added coproduct. Secondly, the calcium carbonatefraction of the coproduct is incorporated into the calcined incominglimestone feed and assimilated into the final cement product. Thisreduces the amount of limestone needed from a quarry.

Trials were performed at the Blue Circle Cement Company manufacturingplant in Harleyville, S.C. Coproduct was introduced to the preheatersection of the kiln at flow rates ranging from 2 to 6.5 tons/hour. Areduction in the quantity of primary fuel coal consistent with the BTUvalue of the coproduct was observed. Additionally, the added calciumcarbonate fraction in the coproduct was converted into cement ofacceptable quality.

Experiment 5: Roofing Membrane

A roofing membrane is made using preferably about 5 to about 50 weightpercent of the present composition.

What is claimed is:
 1. A composition comprising: a binder comprisingasphalt and a residue wherein said residue is a coproduct of the mediumpressure depolymerization of nylon 6 waste carpet and comprises a blendof polypropylene, styrene butadiene resin and calcium carbonate andessentially no residual nylon 6 polyamide material.
 2. The compositionof claim 1 wherein said composition has improved hardness compared tosaid asphalt alone.
 3. The composition of claim 1 wherein saidcomposition has improved rut resistance compared to said asphalt alone.4. The composition of claim 1 wherein said composition has improvedfatigue resistance compared to said asphalt alone.
 5. The composition ofclaim 1 wherein said composition has improved healing compared to saidasphalt alone.
 6. The composition of claim 1 wherein said residuecomprises about 2 to about 50 weight percent of said composition.
 7. Thecomposition of claim 1 wherein said residue acts as a plasticizer andwherein said residue is present at about 7.5 weight percent.
 8. Thecomposition of claim 1 wherein said asphalt has a performance grade ofPG 58-28, said residue is present at about 20 weight percent, and saidcomposition has a performance grade of PG 76-28.
 9. The composition ofclaim 1 wherein said polypropylene has a weight average molecular weightfrom about 9,700 daltons to equal to or less than about 10,000 daltons.10. The composition of claim 1 wherein said depolymerization is in theabsence of added catalyst.
 11. The composition of claim 1 furthercomprising aggregate.
 12. The composition of claim 1 wherein said blendcomprises about 63% by weight said calcium carbonate, about 18% byweight said polypropylene, and about 19% by weight said styrenebutadiene rubber.
 13. A method comprising the step of: determining theperformance grade of a composition using a plot of G′ versus G″ whereinsaid composition comprises a binder and a residue wherein said binder isasphalt and wherein said residue is a coproduct of the medium pressuredepolymerization of nylon 6 waste carpet and comprises a blend ofpolypropylene, styrene butadiene rubber and calcium carbonate andessentially no residual nylon 6 polyamide material.
 14. The method ofclaim 13 wherein said residue comprises about 2 to about 50 weightpercent of said composition.
 15. The method of claim 13 wherein saidblend comprises about 63% by weight said calcium carbonate, about 18% byweight said polypropylene, and about 19% by weight said styrenebutadiene rubber.